The subject matter disclosed herein relates generally to growing crystals, such as crystal growth including a Modified Horizontal Bridgeman (MHB) method.
Growing crystals using the MHB method may be performed by moving a furnace having a fixed temperature profile along a horizontal crucible that contains, at a first step of the growth, a melted material. Alternatively, the MHB may be performed by moving a controlled temperature profile in a fixed furnace along the crucible. In both of these methods, the temperature profile typically includes three zones: the first zone having a temperature that is higher than the melting temperature of the grown material, the second intermediate zone is a transition zone in which the temperature is changed gradually from the temperature of the first zone to that of the third zone and the third zone having a temperature below the melting temperature of the grown material.
The relative movement between the crucible and the temperature profile causes the melted material to gradually change temperature from being above a melting point to be below the melting point of the material. Accordingly, the phase transition of the grown material is controlled to be gradual and slow enough to allow the material to solidify by a crystallization process to produce a solid material in the form of a crystal.
During the crystallization, the conventional process may start in several nucleation (crystallization) centers in which each nucleation center may be in a different crystal-orientation and may have a different potential energy. In crystals that have a preferred crystal-orientation having potential energy that is significantly lower than the potential energy of the other crystal-orientations, the preferred orientation may take over the other crystal-orientations and the grown crystal may be close to a single crystal.
However, in crystals, such as a Cadmium Zinc Telluride (CdZnTe or CZT) crystal, there is no strongly preferred crystal-orientation, which has a significantly lower potential energy to be the crystal orientation that takes over the other crystal orientations during the crystal growth. Accordingly, the growth of the crystal that may start with several nucleation centers may continue to grow with several crystal-orientations, resulting in a polycrystalline grown boule (ingot) having multiple grains and a poor crystalline quality for some applications, such as for detectors for imaging applications.